The present invention relates to a sheet post-processing apparatus, particularly for binding a stack of sheets.
In some prior image forming apparatuses including copiers, printers, facsimile machines, and machines combining the same, there is a type such that sheets discharged from an image forming apparatus is piled, and a piled sheet bundle is stapled or stitched together by a post-processing apparatus disposed therein.
Such sheet post-processing apparatuses have a stitching unit having a head unit for driving staples, and an anvil unit for receiving and bending the staples driven out of the head unit. This allows not only end stitching in which stapling is made on edges of the sheet bundle, but also so-called saddle stitching in which stapling is made at about center portion of the sheet bundle.
The prior sheet post-processing apparatus, as disclosed in Japanese Patent Publication (KOKAI) No. 07-157180, has a partial guide disposed directly on the head unit and the anvil unit for guiding the sheet bundle passing through between the head unit and the anvil unit.
However, the prior sheet post-processing apparatuses have the guide extending partially in the width direction of the sheet bundle. The width direction of the sheet bundle is a direction traversing the sheet bundle feed direction and virtually parallel to the sheet bundle facing the head unit and the anvil unit.
For this reason, some prior sheet post-processing apparatuses have such disadvantages that the partial guide can not guide and support the sheet bundle for the whole width. As a result, edges of the sheet bundle in the width direction are hung down when the sheet bundle is fed or stapled thereon, or the sheet bundle is too deformed in posture to stitch correctly, or the edges of the sheet bundle are folded after stitching.
Other sheet post-processing apparatuses, on the other hand, have the guide extending over virtually entire width of the sheet bundle. The guide can guide and support the entire width. However, the sheet post-processing apparatuses also have the disadvantage such that the sheet bundle is caught on the extending edge by the space between the head unit and the anvil unit. As a result, the sheet bundle is too deformed in posture to stitch correctly, or the edge of the sheet bundle is folded after stitching.
In view of the foregoing problem of the prior art, it is an object of the present invention to provide a sheet post-processing apparatus, wherein a sheet bundle can be fed securely and stitched correctly, and an image forming apparatus having the same therein.
Further objects and advantages of the invention will be apparent from the following description of the invention.
In one aspect of the present invention, a sheet post-processing apparatus comprises a head portion for driving a staple into a sheet bundle; an anvil portion opposingly arranged to the head portion for receiving and bending the staple driven from the head portion; feeding means for feeding or passing the sheet bundle between the head portion and the anvil portion; a guide member positioned between the head portion and the anvil portion for guiding the sheet bundle; and an auxiliary guide member disposed on an upstream side of the guide member in a sheet bundle feed direction of the sheet bundle fed by the feeding means. The auxiliary guide member leads the sheet bundle to the guide member without touching a leading edge of the sheet bundle fed by the feeding means on an upstream edge of the guide member in the sheet bundle feed direction.
In accordance with another aspect of the invention, a sheet post-processing apparatus comprises a head portion for driving a staple into a sheet bundle; an anvil portion opposingly arranged to the head portion for receiving and bending the staple driven from the head portion; feeding means for feeding or passing the sheet bundle between the head portion and the anvil portion; a guide member positioned between the head portion and the anvil portion for guiding the sheet bundle; moving means for moving the head portion and the anvil portion in a direction traversing a sheet bundle feed direction of the sheet bundle fed by the feeding means; and an auxiliary guide member disposed on an upstream side of the guide member in the sheet bundle feed direction of the sheet bundle fed by the feeding means. The auxiliary guide member leads the sheet bundle to the guide member without touching a leading edge of the sheet bundle fed by the feeding means on an upstream edge of the guide member in the sheet bundle feed direction.
In accordance with a further aspect of the present invention, an image forming apparatus comprises an image forming portion; a head portion for driving a staple on a sheet bundle discharged from the image forming portion and stacked; an anvil portion opposingly arranged to the head portion for receiving and bending the staple driven from the head portion; feeding means for feeding or passing the sheet bundle between the head portion and the anvil portion; a guide member positioned between the head portion and the anvil portion for guiding the sheet bundle; an auxiliary guide member disposed on an upstream side of the guide member in the direction of a sheet bundle fed by the feeding means; and a stacking portion for stacking the sheet bundle stitched by the head portion and the anvil portion. The auxiliary guide member leads the sheet bundle to the guide member without touching a leading edge of the sheet bundle fed by the feeding means on an upstream edge of the guide member in the sheet bundle feed direction.